Fluid supply mechanism for multiple fluids to multiple spaced orifices

ABSTRACT

This patent describes an improved form of ink supply to an ink supply head for printing images. The supply is required for a number of different fluids to be supplied to a plurality of different supply slots, the supply slots being spaced apart at periodic intervals in an interleaved manner. The supply includes a fluid inlet portion for each of the plurality of different fluids and a main channel flow portion for each of the different fluids, connected to the fluid inlet portion and running past each of the supply slots; and a sub-channel flow portion connecting each of the supply slots to a corresponding main channel flow portion; two of the main channel flow portion run along the first surface of a moulded flow supply unit and another of the main channel flow portion runs along the top surface of the moulded piece with the subchannel flow portion being interconnected with the slots by way of through-holes through the surface of the the moulded piece. The supply member can be plastic injection moulded and the pitch rate of the slots can be 1,000 slots per inch.

CROSS REFERENCES TO RELATED APPLICATIONS

The following Australian provisional patent applications are herebyincorporated by cross-reference. For the purposes of location andidentification, U.S. patent applications identified by their U.S. patentapplication serial numbers (USSN) are listed alongside the Australianapplications from which the U.S. patent applications claim the right ofpriority.

CROSS-REFERENCED U.S. PATENT APPLICATION AUSTRALIAN (CLAIMING RIGHT OFPROVISIONAL PRIORITY FROM AUSTRALIAN DOCKET PATENT NO. PROVISIONALAPPLICATION) NO. PO7991 09/113,060 ART01 PO8505 09/113,070 ART02 PO798809/113,073 ART03 PO9395 09/112,748 ART04 PO8017 09/112,747 ART06 PO801409/112,776 ART07 PO8025 09/112,750 ART08 PO8032 09/112,746 ART09 PO799909/112,743 ART10 PO7998 09/112,742 ART11 PO8031 09/112,741 ART12 PO803009/112,740 ART13 PO7997 09/112,739 ART15 PO7979 09/113,053 ART16 PO801509/112,738 ART17 PO7978 09/113,067 ART18 PO7982 09/113,063 ART19 PO798909/113,069 ART20 PO8019 09/112,744 ART21 PO7980 09/113,058 ART22 PO801809/112,777 ART24 PO7938 09/113,224 ART25 PO8016 09/112,804 ART26 PO802409/112,805 ART27 PO7940 09/113,072 ART28 PO7939 09/112,785 ART29 PO850109/112,797 ART30 PO8500 09/112,796 ART31 PO7987 09/113,071 ART32 PO802209/112,824 ART33 PO8497 09/113,090 ART34 PO8020 09/112,823 ART38 PO802309/113,222 ART39 PO8504 09/112,786 ART42 PO8000 09/113,051 ART43 PO797709/112,782 ART44 PO7934 09/113,056 ART45 PO7990 09/113,059 ART46 PO849909/113,091 ART47 PO8502 09/112,753 ART48 PO7981 09/113,055 ART50 PO798609/113,057 ART51 PO7983 09/113,054 ART52 PO8026 09/112,752 ART53 PO802709/112,759 ART54 PO8028 09/112,757 ART56 PO9394 09/112,758 ART57 PO939609/113,107 ART58 PO9397 09/112,829 ART59 PO9398 09/112,792 ART60 PO939909/112,791 ART61 PO9400 09/112,790 ART62 PO9401 09/112,789 ART63 PO940209/112,788 ART64 PO9403 09/112,795 ART65 PO9405 09/112,749 ART66 PP095909/112,784 ART68 PP1397 09/112,783 ART69 PP2370 09/112,781 DOT01 PP237109/113,052 DOT02 PO8003 09/112,834 Fluid01 PO8005 09/113,103 Fluid02PO9404 09/113,101 Fluid03 PO8066 09/112,751 IJ01 PO8072 09/112,787 IJ02PO8040 09/112,802 IJ03 PO8071 09/112,803 IJ04 PO8047 09/113,097 IJ05PO8035 09/113,099 IJ06 PO8044 09/113,084 IJ07 PO8063 09/113,066 IJ08PO8057 09/112,778 IJ09 PO8056 09/112,779 IJ10 PO8069 09/113,077 IJ11PO8049 09/113,061 IJ12 PO8036 09/112,818 IJ13 PO8048 09/112,816 IJ14PO8070 09/112,772 IJ15 PO8067 09/112,819 IJ16 PO8001 09/112,815 IJ17PO8038 09/113,096 IJ18 PO8033 09/113,068 IJ19 PO8002 09/113,095 IJ20PO8068 09/112,808 IJ21 PO8062 09/112,809 IJ22 PO8034 09/112,780 IJ23PO8039 09/113,083 IJ24 PO8041 09/113,121 IJ25 PO8041 09/113,122 IJ26PO8037 09/112,793 IJ27 PO8043 09/112,794 IJ28 PO8042 09/113,128 IJ29PO8064 09/113,127 IJ30 PO9389 09/112,756 IJ31 PO9391 09/112,755 IJ32PP0888 09/112,754 IJ33 PP0891 09/112,811 IJ34 PP0890 09/112,812 IJ35PP0873 09/112,813 IJ36 PP0993 09/112,814 IJ37 PP0890 09/112,764 IJ38PP1398 09/112,765 IJ39 PP2592 09/112,767 IJ40 PP2593 09/112,768 IJ41PP3991 09/112,807 IJ42 PP3987 09/112,806 IJ43 PP3985 09/112,820 IJ44PP3983 09/112,821 IJ45 PO7935 09/112,822 IJM01 PO7936 09/112,825 IJM02PO7937 09/112,826 IJM03 PO8061 09/112,827 IJM04 PO8054 09/112,828 IJM05PO8065 09/113,111 IJM06 PO8055 09/113,108 IJM07 PO8053 09/113,109 IJM08PO8078 09/113,123 IJM09 PO7933 09/113,114 IJM10 PO7950 09/113,115 IJM11PO7949 09/113,129 IJM12 PO8060 09/113,124 IJM13 PO8059 09/113,125 IJM14PO8073 09/113,126 IJM15 PO8076 09/113,119 IJM16 PO8075 09/113,120 IJM17PO8079 09/113,221 IJM18 PO8050 09/113,116 IJM19 PO8052 09/113,118 IJM20PO7948 09/113,117 IJM21 PO7951 09/113,113 IJM22 PO8074 09/113,130 IJM23PO7941 09/113,110 IJM24 PO8077 09/113,112 IJM25 PO8058 09/113,087 IJM26PO8051 09/113,074 IJM27 PO8045 09/113,089 IJM28 PO7952 09/113,088 IJM29PO8046 09/112,771 IJM30 PO9390 09/112,769 IJM31 PO9392 09/112,770 IJM32PP0889 09/112,798 IJM35 PP0887 09/112,801 IJM36 PP0882 09/112,800 IJM37PP0874 09/112,799 IJM38 PP1396 09/113,098 IJM39 PP3989 09/112,833 IJM40PP2591 09/112,832 IJM41 PP3990 09/112,831 IJM42 PP3986 09/112,830 IJM43PP3984 09/112,836 IJM44 PP3982 09/112,835 IJM45 PP0895 09/113,102 IR01PP0870 09/113,106 IR02 PP0869 09/113,105 IR04 PP0887 09/113,104 IR05PP0885 09/112,810 IR06 PP0884 09/112,766 IR10 PP0886 09/113,085 IR12PP0871 09/113,086 IR13 PP0876 09/113,094 IR14 PP0877 09/112,760 IR16PP0878 09/112,773 IR17 PP0879 09/112,774 IR18 PP0883 09/112,775 IR19PP0880 09/112,745 IR20 PP0881 09/113,092 IR21 PO8006 09/113,100 MEMS02PO8007 09/113,093 MEMS03 PO8008 09/113,062 MEMS04 PO8010 09/113,064MEMS05 PO8011 09/113,082 MEMS06 PO7947 09/113,081 MEMS07 PO794409/113,080 MEMS09 PO7946 09/113,079 MEMS10 PO9393 09/113,065 MEMS11PP0875 09/113,078 MEMS12 PP0894 09/113,075 MEMS13

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to the supply of fluid, such as inks orthe like to a mechanism such as a printhead which consumes the inksupplied.

BACKGROUND OF THE INVENTION

Recently, small compact printheads have been proposed for page widthprintheads with the printheads operating at high speeds and, in a pagewidth manner, for the printing out of ink. A printhead able to printfull color pictures relies upon the supply of at least three inks (cyan,magenta and yellow) and, when operated in a pagewidth manner, is likelyto consume a substantial amount of ink.

Recently, a page width printhead has been proposed having full coloroutput capabilities. A problem in providing a full color slim pagewidthinkjet head is the supply of ink to the ink jet head. Obviously, anumber of different colored inks have to be supplied to ink ejectionchambers within an ink jet head in a continuous manner so as to supporthigh speed operation.

Further, any system of ink supply must be compact and suitable forincorporation into any printing system utilizing the supply.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved form ofink supply to an ink supply head for printing images.

In accordance with a first aspect of the present invention, there isprovided a fluid supply means for supplying a plurality of differentfluids to a plurality of different supply slots, wherein the supplyslots are being spaced apart at periodic intervals in an interleavedmanner, the fluid supply means comprising a fluid inlet means for eachof the plurality of different fluids, a main channel flow means for eachof the different fluids, connected to said fluid inlet means and runningpast each of the supply slots, and sub-channel flow means connectingeach of the supply slots to a corresponding main channel flow means. Thenumber of fluids is greater than 2 and at least two of the main channelflow means run along the first surface of a moulded flow supply unit andanother of the main channel flow means runs along the top surface of themoulded piece with the subchannel flow means being interconnected withthe slots by means of through-holes through the surface of the mouldedpiece.

Preferably, the supply means is plastic injection moulded and the pitchrate of the slots is substantially less than, or equal to 1,000 slotsper inch. Further the collection of slots runs substantially the widthof a photograph. Preferably, the fluid supply means further comprises aplurality of roller slot means for the reception of one or more pinchrollers and the fluid comprises ink and the rollers are utilised tocontrol the passage of a print media across a printhead interconnectedto the slots. The slots are divided into corresponding colour slots witheach series of colour slots being arranged in columns.

Preferably, at least one of the channels of the fluid supply means isexposed when fabricated and is sealed by means of utilising sealing tapeto seal the exposed surface of the channel. Advantageously, the fluidsupply means is further provided with a TAB slot for the reception oftape automated bonded (TAB) wires.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of thepresent invention, preferred forms of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings which:

FIG. 1. illustrates an exploded perspective in section of a printingsystem;

FIG. 2. illustrates a perspective view, partly in section of theink-head supply unit of FIG. 1;

FIG. 3. illustrates a bottom perspective view, partly in section, of theink-head supply unit of FIG. 1;

FIG. 4. illustrates an enlarged top view of the ink-head supply unit ofFIG. 1;

FIG. 5. illustrates an enlarged bottom view, partly in section, of theink-head supply unit of FIG. 1;

FIGS. 6 and 7 illustrate perspective views of the ink-head supply unitillustrate placement of rollers therein;

FIG. 8 illustrates a plan view of the ink-head supply unit providingfurther details on the flow of ink within the ink-head supply unit.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In the preferred embodiment, there is provided an inkjet in supply meansfor the supply of ink to a pagewidth printhead, the width of the pagebeing variable in accordance to requirements.

Turning initially to FIG. 1, there is illustrated 1 an explodedperspective view, in section, of a full printing system 1 is basedaround a printhead 2 which ejects ink drops on demand on to print media3 so as to form an image. The print media 3 is pinched between two setof rollers comprising a first set 5, 6 and second set 7, 8.

The printhead 2 operates under the control of power, ground and signallines 10 which provide power and control for the printhead 2 and arebonded by means of Tape Automated Bonding (TAB) to the surface of theprinthead 2.

Importantly, the printhead 2, which can be constructed from a siliconwafer device suitably separated, relies upon a series of anisotropicetches 12 through the wafer having near vertical side walls. The throughwafer etches 12 allow for the direct supply of ink to the printheadsurface from the back of the wafer for subsequent ejection.

The ink is supplied to the back of the ink jet head 2 by means ofink-head supply unit 14. The ink jet head 2 has three separate rowsalong its surface for the supply of separate colors of ink. The ink headsupply unit 14 also includes a lid 15 for the sealing of ink channels.

In FIGS. 2-7, there is illustrated various perspective views of theink-head supply unit 14. Each of FIGS. 2-7 illustrate only a portion ofthe supply unit which can be constructed of indefinite length, portionsonly as shown so as to provide exemplary details. In FIG. 2, there isillustrated a bottom perspective view, FIG. 3 illustrates a topperspective view, FIG. 4 illustrates a close up bottom perspective view,partly in sections, FIG. 5 illustrates a top side perspective viewshowing details of the ink channels, and FIG. 6 illustrates a top sideperspective view as does FIG. 7.

There is considerable cost advantage in forming ink-head supply unit 14from injection moulded plastic instead of, say, micromachined silicon.The manufacturing cost of a plastic ink channel will be considerablyless in volume and manufacturing is substantially easier. The designillustrated in the accompanying drawings assumes a 1600 dpi three colormonolithic print head, of a predetermined length. The provided flow ratecalculations are for a 100 mm photo printer.

The ink-head supply unit 14 contains all of the required fine details.The lid 15 (FIG. 1) is permanently glued or ultrasonically welded to theink-head supply unit 14 and provides a seal for the ink channels.

Turning to FIG. 2, the cyan, magenta and yellow ink flows in through inkinlets 20-22, the magenta ink flows through the through-holes 24,25 andalong the magenta main channels 26,27 (FIG. 3). The cyan ink flows alongcyan main channel 30 and the yellow ink flows along the yellow mainchannel 31. As best seen if FIG. 4, the cyan ink in the cyan mainchannels then flows into a cyan subchannel 33. The yellow subchannel 34similarly receiving yellow ink from the yellow main channel 31.

As best seen in FIG. 5, the magenta ink also flows from magenta mainchannels 26,27 through magenta through-holes 36, 37. Returning again toFIG. 4, the magenta ink flows out of the through-holes 36, 37. Themagenta ink flows along first magenta subchannel e.g. 38 and then alongsecond magenta subchannel e.g. 39 before flowing into a magenta pit area40. The magenta ink then flows through magenta vias e.g. 42 which arealigned with corresponding inkjet head through-holes (e.g. 12 of FIG. 1)wherein they subsequently supply ink to inkjet nozzles for printing out.

Similarly, the cyan ink within the cyan subchannel 33 flows into a cyanpit area 49 which supplies ink two cyan vias 43, 44. Similarly, theyellow subchannel 34 supplies yellow pit area 46 which in turn suppliesyellow vias 47, 48.

As seen in FIG. 5, the printhead is designed to be received withinprinthead slot 50 wilt the various vias e.g. 51 aligned withcorresponding through holes, e.g. 12 in the printhead wafer (FIG. 1).

Returning to FIG. 1, care must be taken to provide adequate ink flow tothe entire printhead chip 2, while satisfying the constrains of aninjection moulding process. The size of the ink through wafer holes 12at the back of the print head chip is approximately 100 μm×50 μm, andthe spacing between through holes carrying different colors of ink isapproximately 170 μm. While features of this size can readily be mouldedin plastic (compact discs have micron sized features), ideally the wallheight must not exceed a few times the wall thickness so as to maintainadequate stiffness. The preferred embodiment overcomes these problems byusing a hierarchy of progressively smaller ink channels.

In FIG. 8, there is illustrated schematically, a section of anarrangement 70 of the printhead 2 of FIG. 1. The section is divided into3 series of nozzles comprising the cyan series 71, the magenta series 72and the yellow series 73. Each series of nozzles is further divided intotwo rows, e.g. 75, 76 with the printhead 70 having a series of bond pads78 for bonding of power in control signals.

The printhead includes the ink supply channels, e.g. 81, equivalent toanisotropic edge hole 12 of FIG. 1. The ink flows from the back of thewafer through supply channel 81 and in turn through the filter grills,e.g. 82, to ink nozzle chambers, e.g. 83. The operation of the nozzlechamber 83 and printhead 2 (FIG. 1) is, as mentioned previously, perdescribed in the abovementioned patent specification.

Ink Channel Fluid Flow Analysis

Turning now to an analysis of the ink flow, the main ink channels 26,27, 30, 31 (FIG. 2, FIG. 3) are around 1 mm×1 mm, and supply all of thenozzles of one color. The subchannels 33, 34, 38, 39 (FIG. 4) are around200 μm x 100 μm and supply about 25 inkjet nozzles each. The printheadthrough holes 43, 44, 47, 48 and water through holes, e.g. 81 (FIG. 10)are 100 μm×50 μm and supply 3 nozzles at each side of the print headthrough holes. Each nozzle filter 82 has 8 slits, each with an area of20 μm×2 μm and supplies a single nozzle.

An analysis has been conducted of the pressure requirements of an inkjet printer constructed as described. The analysis is for a 1,600 dpithree color process printhead for photograph printing. The print widthwas 100 mm which gives 6,250 nozzles for each color, giving a total of18,750 nozzles.

The maximum ink flow rate required in various channels for full blackprinting is important. It determines the pressure drop along the inkchannels, and therefore whether the printhead will stay filled by thesurface tension forces alone, or, if not, the ink pressure that isrequired to keep the printhead full.

To calculate the pressure drop, a drop volume of 2.5 pl for 1,600 dpioperation was utilized.

While the nozzles may be capable of operating at a higher rate, thechosen drop repetition rate is 5 KHz which is suitable to print a 150 mmlong photograph in an little under 2 seconds. Thus, the printhead, inthe extreme case, has a 18,750 nozzles, all printing a maximum of 5,000drops per second. This ink flow is distributed over the hierarchy of inkchannels. Each ink channel effectively supplies a fixed number ofnozzles when all nozzles are printing.

The pressure drop Ap was calculated according to the Darcy-Weisbachformula: ${\Delta\rho} = \frac{\rho \quad U^{2}{fL}}{2D}$

Where ρ is the density of the ink, U is the average flow velocity, L isthe length, D is the hydraulic diameter, and first a dimensionlessfriction factor calculated as follows: $f = \frac{k}{Re}$

Where Re is the Reynolds number and k is a dimensionless frictioncoefficient dependant upon the cross section of the channel, bothcalculated as follows: ${Re} = \frac{UD}{v}$

Where υ is the kinematic viscosity of the ink, and for a rectangularcross section, k can be approximated by:$k = \frac{64}{\frac{2 + {11b}}{3\quad 24a}\frac{11b}{24a}\left( {2 - {b/a}} \right)}$

Where a is the longest side of the rectangular cross section, and b isthe shortest side. The hydraulic diameter D for a rectangular crosssection is given by: $D = \frac{2{ab}}{a + b}$

Ink is drawn off the main ink channels at 250 points along the length ofthe channels. The ink velocity falls linearly from the start of thechannel to zero at the end of the channel, so the average flow velocityU is half of the maximum flow velocity. Therefore, the pressure dropalong the main ink channels is half of that calculated using the maximumflow velocity.

Utilizing these formulas, the pressure drops can be calculated inaccordance with the following tables:

Table of Ink Channel Dimensions and Pressure Drops Max. ink PressureNumber Nozzles flow at drop of Items Length Width Depth supplied 5KHz(U) Δρ Central Moulding 1 106 mm 6.4 mm 1.4 mm 18,750 0.23 ml/seC NACyan main channel 1 100 mm 1 mm 1 mm 6,250 0.16 μl/μs 111 Pa (30)Magenta main channel 2 100 mm 700 μm 700 μm 3,125 0.16 μl/μs 231 Pa (26)Yellow main channel 1 100 mm 1 mm 1 mm 6,250 0.16 μl/μs 111 Pa (31) Cyansub-channel (33) 250 1.5 mm 200 μm 100 μm 25 0.16 μl/μs 41.7 Pa Magentasub-channel 500 200 μm 50 μm 100 μm 12.5 0.031 μl/μs 44.5 Pa (34)(a)Magenta sub-channel 500 400 μm 100 μm 200 μm 12.5 0.031 μl/μs 5.6 Pa(38)(b) Yellow sub-channel 250 1.5 mm 200 μm 100 μm 25 0.016 μl/μs 41.7Pa (34) Cyan pit (42) 250 200 μm 100 μm 300 μm 25 0.010 μl/μs 3.2 PaMagenta through (40) 500 200 μm 50 μm 200 μm 12.5 0.016 μl/μs 18.0 PaYellow pit (46) 250 200 μm 100 μm 300 μm 25 0.010 μl/μs 3.2 Pa Cyan via(43) 500 100 μm 50 μm 100 μm 12.5 0.031 μl/μs 22.3 Pa Magenta via (42)500 100 μm 50 μm 100 μm 12.5 0.031 μl/μs 22.3 Pa Yellow via 500 100 μm50 μm 100 μm 12.5 0.031 μl/μs 22.3 Pa Magenta through hole 500 200 μm500 μm 100 μm 12.5 0.0031 μl/μs 0.87 Pa (37) Chip slot 1 100 mm 730 μm625 18,750 NA NA Print head through 1500 600μ 100 μm 50 μm 12.5 0.052μl/μs 133 Pa holes (81)(in the chip substrate) Print head channel 1,000/50 μm 60 μm 20 μm 3.125 0.049 μl/μs 62.8 Pa segments (on chip colorfront) Filter Slits (on 8 per 2 μm 2 μm 20 μm 0.125 0.039 μl/μs 251 Paentrance to nozzle nozzle chamber (82) Nozzle chamber (on 1 per 70 μm 30μm 20 μm 1 0.021 μl/μs 75.4 Pa chip front)(83) nozzle

The total pressure drop from the ink inlet to the nozzle is thereforeapproximately 701 Pa for cyan and yellow, and 845 Pa for magenta. Thisis less than 1% of atmospheric pressure. Of course, when the imageprinted is less than full black, the ink flow (and therefore thepressure drop) is reduced from these values.

Making the Mould for the Ink-head Supply Unit

The ink head supply unit 14 (FIG. 1) has features as small as 50μ and alength of 106 mm. It is impractical to machine the injection mouldingtools in the conventional manner. However, even though the overall shapemay be complex, there are no complex curves required. The injectionmoulding tools can be made using conventional milling for the main inkchannels and other millimetre scale features, with a lithographicallyfabricated inset for the fine features. A LIGA process can be used forthe inset.

A single injection moulding tool could readily have 50 or more cavities,so could make many millions of ink channels per year, at a minimal cost.Most of the tool complexity is in the inset. As the insets arereplicated lithographically, the total toolmaking cost should not beexcessive.

Returning to FIG. 1, the printing system 1 is constructed via mouldingink supply unit 14 and lid 15 together and sealing them together aspreviously described. Subsequently printhead 2 is placed in itscorresponding slot 50. Adhesive sealing strips 52, 53 are placed overthe magenta main channels so to ensure that they are properly sealed.The Tape Automated Bonding (TAB) strip 10 is then connected to theinkjet head 2 with tab bonding wires running in TAB slot 55. As can bestbe seen from FIGS. 6 and 7, aperture slots 56 to 63 are provided for thesnap in insertion of rollers 5, 7 (FIG. 1). The slots provide for the“clipping in” of rollers with a small degree of play subsequently beingprovided for simple rotation of the rollers.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiment without departing from the spirit orscope of the invention as broadly described. The present embodiment is,therefore, to be considered in all respects to be illustrative and notrestrictive.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Ofcourse many different devices could be used. However presently popularink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption.This is approximately 100 times that required for high speed, and stemsfrom the energy-inefficient means of drop ejection. This involves therapid boiling of water to produce a vapor bubble which expels the ink.Water has a very high heat capacity, and must be superheated in thermalink jet applications. This leads to an efficiency of around 0.02%, fromelectricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size andcost. Piezoelectric crystals have a very small deflection at reasonabledrive voltages, and therefore require a large area for each nozzle.Also, each piezoelectric actuator must be connected to its drive circuiton a separate substrate. This is not a significant problem at thecurrent limit of around 300 nozzles per printhead, but is a majorimpediment to the fabrication of pagewidth printheads with 19,200nozzles.

Ideally, the ink jet technologies used meet the stringent requirementsof in-camera digital color printing and other high quality, high speed,low cost printing applications. To meet the requirements of digitalphotography, new ink jet technologies have been created. The targetfeatures include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systemsdescribed below with differing levels of difficulty. Forty-fivedifferent ink jet technologies have been developed by the Assignee togive a wide range of choices for high volume manufacture. Thesetechnologies form part of separate applications assigned to the presentAssignee as set out in the table under the heading Cross References toRelated Applications.

The ink jet designs shown here are suitable for a wide range of digitalprinting systems, from battery powered one-time use digital cameras,through to desktop and network printers, and through to commercialprinting systems.

For ease of manufacture using standard process equipment, the printheadis designed to be a monolithic 0.5 micron CMOS chip with MEMS postprocessing. For color photographic applications, the printhead is 100 mmlong, with a width which depends upon the ink jet type. The smallestprinthead designed is IJ38, which is 0.35 mm wide, giving a chip area of35 square mm. The printheads each contain 19,200 nozzles plus data andcontrol circuitry.

Ink is supplied to the back of the printhead by injection molded plasticink channels. The molding requires 50 micron features, which can becreated using a lithographically micromachined insert in a standardinjection molding tool. Ink flows through holes etched through the waferto the nozzle chambers fabricated on the front surface of the wafer. Theprinthead is connected to the camera circuitry by tape automatedbonding.

Tables of Drop-on-Demand Ink Jets

Eleven important characteristics of the fundamental operation ofindividual ink jet nozzles have been identified. These characteristicsare largely orthogonal, and so can be elucidated as an elevendimensional matrix. Most of the eleven axes of this matrix includeentries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of inkjet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains36.9 billion possible configurations of ink jet nozzle. While not all ofthe possible combinations result in a viable ink jet technology, manymillion configurations are viable. It is clearly impractical toelucidate all of the possible configurations. Instead, certain ink jettypes have been investigated in detail. These are designated IJ01 toIJ45 which matches the docket numbers in the table under the headingCross References to Related Applications.

Other ink jet configurations can readily be derived from theseforty-five examples by substituting alternative configurations along oneor more of the 11 axes. Most of the IJ01 to IJ45 examples can be madeinto ink jet printheads with characteristics superior to any currentlyavailable ink jet technology.

Where there are prior art examples known to the inventor, one or more ofthese examples are listed in the examples column of the tables below.The U01 to U45 series are also listed in the examples column. In somecases, print technology may be listed more than once in a table, whereit shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Homeprinters, Office network printers, Short run digital printers,Commercial print systems, Fabric printers, Pocket printers, Internet WWWprinters, Video printers, Medical imaging, Wide format printers,Notebook PC printers, Fax machines, Industrial printing systems,Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrixare set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) DescriptionAdvantages Disadvantages Examples Thermal An electrothermal Large forceHigh power Canon Bubblejet bubble heater heats the ink to generated Inkcarrier 1979 Endo et al GB above boiling point, Simple limited to waterpatent 2,007,162 transferring significant construction Low efficiencyXerox heater-in- heat to the aqueous No moving parts High pit 1990Hawkins et ink. A bubble Fast operation temperatures al U.S. Pat. No.nucleates and quickly SmaIl chip area required 4,899,181 forms,expelling the required for actuator High mechanical Hewlett-Packard ink.stress TIJ 1982 Vaught et The efficiency of the Unusual al U.S. Pat. No.process is low, with materials required 4,490,728 typically less thanLarge drive 0.05% of the electrical transistors energy being Cavitationcauses transformed into actuator failure kinetic energy of the Kogationreduces drop. bubble formation Large print heads are difficult tofabricate Piezo- A piezoelectric crystal Low power Very large area Kyseret al electric such as lead consumption required for actuator U.S. Pat.No. lanthanum zirconate Many ink types Difficult to 3,946,398 (PZT) iselectrically can be used integrate with Zoltan activated, and eitherFast operation electronics U.S. Pat. No. expands, shears, or Highefficiency High voltage 3,683,212 bends to apply drive transistors 1973Stemme pressure to the ink, required U.S. Pat. No. ejecting drops. Fullpagewidth 3,747,120 print heads Epson Stylus impractical due toTektronix actuator size IJ04 Requires electrical poling in high fieldstrengths during manufacture Electro- An electric field is Low power Lowmaximum Seiko Epson, strictive used to activate consumption strain(approx. Usui et all JP electrostriction in Many ink types 0.01%)253401/96 relaxor materials such can be used Large area IJ04 as leadlanthanum Low thermal required for actuator zirconate titanate expansiondue to low strain (PLZT) or lead Electric field Response speed magnesiumniobate strength required is marginal (˜10 (PMN). (approx. 3.5 V/μm) μs)can be generated High voltage without difficulty drive transistors Doesnot require required electrical poling Full pagewidth print headsimpractical due to actuator size Ferro- An electric field is Low powerDifficult to IJ04 electric used to induce a phase consumption integratewith transition between the Many ink types electronics antiferroelectric(AFE) can be used Unusual and ferroelectric (FE) Fast operationmaterials such as phase. Perovskite (<1 μs) PLZSnT are materials such astin Relatively high required modified lead longitudinal strain Actuatorsrequire lanthanum zirconate High efflciency a large area titanate(PLZSnT) Electric field exhibit large strains of strength of around 3 upto 1% associated V/μm can be readily with the AFE to FE provided phasetransition. Electro- Conductive plates are Low power Difficuit to IJ02,IJ04 static plates separated by a consumption operate electrostaticcompressible or fluid Many ink types devices in an dielectric (usuallyair). can be used aqueous Upon application of a Fast operationenvironment voltage, the plates The electrostatic attract each other andactuator will displace ink, causing normally need to be drop ejection.The separated from the conductive plates may ink be in a comb or Verylarge area honeycomb structure, required to achieve or stacked toincrease high forces the surface area and High voltage therefore theforce. drive transistors may be required Full pagewidth print heads arenot competitive due to actuator size Electro- A strong electric fieldLow current High voltage 1989 Saito et al, static pull is applied to theink, consumption required U.S. Pat. No. on ink whereupon Low temperatureMay be damaged 4,799,068 electrostatic attraction by sparks due to air1989 Miura et al, accelerates the ink breakdown U.S. Pat. No. towardsthe print Required field 4,810,954 medium. strength increases asTone-jet the drop size decreases High voltage drive transistors requiredElectrostatic field attracts dust Permanent An electromagnet Low powerComplex 1J07, IJ10 magnet directly attracts a consumption fabricationelectro- permanent magnet, Many ink types Permanent magnetic displacingink and can be used magnetic material causing drop ejection. Fastoperation such as Neodymium Rare earth magnets High efficiency IronBoron (NdFeB) with a field strength Easy extension required. around 1Tesla can be from single nozzles High local used. Examples are: topagewidth print currents required Samarium Cobalt heads Copper (SaCo)and magnetic metalization should materials in the be used for longneodymium iron boron electromigration family (NdFeB, lifetime and lowNdDyFeBNb, resistivity NdDyFeB, etc) Pigmented inks are usuallyinfeasible Operating temperature limited to the Curie temperature(around 540 K) Soft A solenoid induced a Low power Complex IJ01, IJ05,IJ08, magnetic magnetic field in a soft consumption fabrication IJ10,IJ12, IJ14, core electro- magnetic core or yoke Many ink types Materialsnot IJ15, IJ17 magnetic fabricated from a can be used usually present ina ferrous material such Fast operation CMOS fab such as as electroplatediron High efficiency NiFe, CoNiFe, or alloys such as CoNiFe Easyextension CoFe are required [1], CoFe, or NiFe from single nozzles Highlocal alloys. Typically, the to pagewidth print currents required softmagnetic material heads Copper is in two parts, which metalizationshould are normally held be used for long apart by a spring.electromigration When the solenoid is lifetime and low actuated, the twoparts resistivity attract, displacing the Electroplating is ink.required High saturation flux density is required (2.0-2.1 T isachievable with CoNiFe [1]) Lorenz The Lorenz force Low power Force actsas a IJ06, IJ11, IJ13, force acting on a current consumption twistingmotion IJ16 carrying wire in a Many ink types Typically, only a magneticfield is can be used quarter of the utilized. Fast operation solenoidlength This allows the High efficiency provides force in a magneticfietd to be Easy extension useful direction supplied externally to fromsingle nozzles High local the print head, for to pagewidth printcurrents required example with rare heads Copper earth permanentmetalization should magnets. be used for long Only the currentelectromigration carrying wire need be lifetime and low fabricated onthe print- resistivity head, simplifying Pigmented inks materials areusually requirements. infeasible Magneto- The actuator uses the Many inktypes Force acts as a Fischenbeck, striction giant magnetostrictive canbe used twisting motion U.S. Pat. No. effect of materials Fast operationUnusual 4,032,929 such as Terfenol-D (an Easy extension materials suchas IJ25 alloy of terbium, from single nozzles Terfenol-D are dysprosiumand iron to pagewidth print required developed at the Naval heads Highlocal Ordnance Laboratory, High force is currents required henceTer-Fe-NOL). available Copper For best efficiency, the metalizationshould actuator should be pre- be used for long stressed to approx. 8electromigration MPa. lifetime and low resistivity Pre-stressing may berequired Surface Ink under positive Low power Requires Silverbrook, EPtension pressure is held in a consumption supplementary force 0771 658A2 and reduction nozzle by surface Simple to effect drop related patenttension. The surface construction separation applications tension of theink is No unusual Requires special reduced below the materials requiredin ink surfactants bubble threshold, fabrication Speed may be causingthe ink to High efficiency limited by surfactant egress from the Easyextension properties nozzle. from single nozzles to pagewidth printheads Viscosity The ink viscosity is Simple Requires Silverbrook, EPreduction locally reduced to construction supplementary force 0771 658A2 and select which drops are No unusual to effect drop related patentto be ejected. A materials required in separation applications viscosityreduction can fabrication Requires special be achieved Easy extensionink viscosity electrothermally with from single nozzles properties mostinks, but special to pagewidth print High speed is inks can beengineered heads difficult to achieve for a 100:1 viscosity Requiresreduction. oscillating ink pressure A high temperature difference(typically 80 degrees) is required Acoustic An acoustic wave is Canoperate Complex drive 1993 Hadimioglu generated and without a nozzlecircuitry et al, EUP 550,192 focussed upon the plate Complex 1993 Elrodet al, drop ejection region. fabrication EUP 572,220 Low efficiency Poorcontrol of drop position Poor control of drop volume Thermo- An actuatorwhich Low power Efficient aqueous IJ03, IJ09, IJ17, elastic bend reliesupon differential consumption operation requires a IJ18, IJ19, IJ20,actuator thermal expansion Many ink types thermal insulator on IJ21,IJ22, IJ23, upon Joule heating is can be used the hot side IJ24, IJ27,IJ28, used. Simple planar Corrosion IJ29, IJ30, IJ31, fabricationprevention can be IJ32, IJ33, IJ34, Small chip area difficult IJ35,IJ36, IJ37, required for each Pigmented inks IJ38 ,IJ39, IJ40, actuatormay be infeasible, IJ41 Fast operation as pigment particles Highefficiency may jam the bend CMOS actuator compatible voltages andcurrents Standard MEMS processes can be used Easy extension from singlenozzles to pagewidth print heads High CTE A material with a very Highforce can Requires special IJ09, IJ17, IJ18, thermo- high coefficient ofbe generated material (e.g. PTFE) IJ20, IJ21, 1322, elastic thermalexpansion Three methods of Requires a PTFE IJ23, IJ24, IJ27, actuator(CTE) such as PTFE deposition are deposition process, IJ28, IJ29, IJ30,polytetrafluoroethylene under development: which is not yet IJ31, IJ42,IJ43, (PTFE) is used. As chemical vapor standard in ULSI IJ44 high CTEmaterials deposition (CVD), fabs are usually non- spin coating, and PTFEdeposition conductive, a heater evaporation cannot be followedfabricated from a PTFE is a with high conductive material is candidatefor low temperature (above incorporated. A 50 μm dielectric constant350° C.) processing long PTFE bend insulation in ULSI Pigmented inksactuator with Very low power may be infeasible, polysilicon heater andconsumption as pigment particles 15 mW power input Many ink types mayjam the bend can provide 180 μN can be used actuator force and 10 μmSimple planar deflection. Actuator fabrication motions include: Smallchip area Bend required for each Push actuator Buckle Fast operationRotate High efficiency CMOS compatible voltages and currents Easyextension from single nozzles to pagewidth print heads Conduct-ive Apolymer with a high High force can Requires special IJ24 polymercoefficient of thermal be generated materials thermo- expansion (such asVery low power development (High elastic PTFE) is doped with consumptionCTE conductive actuator conducting substances Many ink types polymer) toincrease its can be used Requires a PTFE conductivity to about 3 Simpleplanar deposition process, orders of magnitude fabrication which is notyet below that of copper. Small chip area standard in ULSI Theconducting required for each fabs polymer expands actuator PTFEdeposition when resistively Fast operation cannot be followed heated.High efficiency with high Examples of CMOS temperature (above conductingdopants compatible voltages 350° C.) processing include: and currentsEvaporation and Carbon nanotubes Easy extension CVD deposition Metalfibers from single nozzles techniques cannot Conductive polymers topagewidth print be used such as doped heads Pigmented inks polythiophenemay be infeasible, Carbon granules as pigment particles may jam the bendactuator Shape A shape memory alloy High force is Fatigue limits IJ26memory such as TiNi (also available (stresses maximum number alloy knownas Nitinol - of hundreds of MPa) of cycles Nickel Titanium alloy Largestrain is Low strain (1%) developed at the Naval available (more than isrequired to extend Ordnance Laboratory) 3%) fatigue resistance isthermally switched High corrosion Cycle rate between its weak resistancelimited by heat martensitic state and Simple removal its high stiffnessconstruction Requires unusual austenic state. The Easy extensionmaterials (TiNi) shape of the actuator from single nozzles The latentheat of in its martensitic state to pagewidth print transformation mustis deformed relative to heads be provided the austenic shape. Lowvoltage High current The shape change operation operation causesejection of a Requires pre- drop. stressing to distort the martensiticstate Linear Linear magnetic Linear Magnetic Requires unusual IJ12Magnetic actuators include the actuators can be semiconductor ActuatorLinear Induction constructed with materials such as Actuator (LIA),Linear high thrust, long soft magnetic alloys Permanent Magnet travel,and high (e.g. CoNiFe) Synchronous Actuator efficiency using Somevarieties (LPMSA), Linear planar also require Reluctance semiconductorpermanent magnetic Synchronous Actuator fabrication materials such as(LRSA), Linear techniques Neodymium iron Switched Reluctance Longactuator boron (NdFeB) Actuator (LSRA), and travel is available Requiresthe Linear Stepper Medium force is complex multi- Actuator (LSA).available phase drive circuitry Low voltage High current operationoperation

BASIC OPERATION MODE Description Advantages Disadvantages ExamplesActuator This is the simplest Simple operation Drop repetition Thermalink jet directly mode of operation: the No external rate is usuallyPiezoelectric ink pushes ink actuator directly fields required limitedto around 10 jet supplies sufficient Satellite drops kHz. However, thisIJ01, IJ02, IJ03, kinetic energy to expel can be avoided if is notfundamental IJ04, IJ05, IJ06, the drop. The drop drop velocity is lessto the method, but is 1J07, IJ09, IJ11, must have a sufficient than 4m/s related to the refill IJ12, IJ14, IJ16, velocity to overcome Can beefficient, method normally IJ20, IJ22, IJ23, the surface tension.depending upon the used IJ24, IJ25, IJ26, actuator used All of the dropIJ27, IJ28, IJ29, kinetic energy must IJ30, IJ31, IJ32, be provided bythe IJ33, IJ34, IJ35, actuator IJ36, IJ37, IJ38, Satellite drops IJ39,IJ40, IJ41, usually form if drop IJ42, IJ43, IJ44 velocity is greaterthan 4.5 m/s Proximity The drops to be Very simple print Requires closeSilverbrook, EP printed are selected by head fabrication can proximitybetween 0771 658 A2 and some manner (e.g. be used the print head andrelated patent thermally induced The drop the print media orapplications surface tension selection means transfer roller reductionof does not need to May require two pressurized ink). provide the energyprint heads printing Selected drops are required to separate alternaterows of the separated from the ink the drop from the image in the nozzleby nozzle Monolithic color contact with the print print heads are mediumor a transfer difficult roller. Electro- The drops to be Very simpleprint Requires very Silverbrook, EP static pull printed are selected byhead fabrication can high electrostatic 0771 658 A2 and on ink somemanner (e.g. be used field related patent thermally induced The dropElectrostatic field applications surface tension selection means forsmall nozzle Tone-Jet reduction of does not need to sizes is above airpressurized ink). provide the energy breakdown Selected drops arerequired to separate Electrostatic field separated from the ink the dropfrom the may attract dust in the nozzle by a nozzle strong electricfield. Magnetic The drops to be Very simple print Requires Silverbrook,EP pull on ink printed are selected by head fabrication can magnetic ink0771 658 A2 and some manner (e.g. be used Ink colors other relatedpatent thermally induced The drop than black are applications surfacetension selection means difficult reduction of does not need to Requiresvery pressurized ink). provide the energy high magnetic fields Selecteddrops are required to separate separated from the ink the drop from thein the nozzle by a nozzle strong magnetic field acting on the magneticink. Shutter The actuator moves a High speed (>50 Moving parts are IJ13,IJ17, IJ21 shutter to block ink kHz) operation can required flow to thenozzle. The be achieved due to Requires ink ink pressure is pulsedreduced refill time pressure modulator at a multiple of the Drop timingcan Friction and wear drop ejection be very accurate must be consideredfrequency. The actuator Stiction is energy can be very possible lowShuttered The actuator moves a Actuators with Moving parts are IJ08,IJ15, IJ18, grill shutter to block ink small travel can be required IJ19flow through a grill to used Requires ink the nozzle. The shutterActuators with pressure modulator movement need only small force can beFriction and wear be equal to the width used must be considered of thegrill holes. High speed (>50 Stiction is kHz) operation can possible beachieved Pulsed A pulsed magnetic Extremely low Requires an IJ10magnetic field attracts an ‘ink energy operation is external pulsed pullon ink pusher’ at the drop possible magnetic field pusher ejectionfrequency. An No heat Requires special actuator controls a dissipationmaterials for both catch, which prevents problems the actuator and thethe ink pusher from ink pusher moving when a drop is Complex not to beejected. construction

AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description AdvantagesDisadvantages Examples None The actuator directly Simplicity of Dropejection Most ink jets, fires the ink drop, and construction energy mustbe including there is no external Simplicity of supplied bypiezoelectric and field or other operation individual nozzle thermalbubble. mechanism required. Small physical actuator IJ01, IJ02, IJ03,size IJ04, IJ05, IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24,IJ25, IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36,IJ37 IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The inkpressure Oscillating ink Requires external Silverbrook, EP ink pressureoscillates, providing pressure can provide ink pressure 0771 658 A2 and(including much of the drop a refill pulse, oscillator related patentacoustic ejection energy. The allowing higher Ink pressure applicationsstimul- actuator selects which operating speed phase and amplitude IJ08,IJ13, IJ15, ation) drops are to be fired The actuators must be carefullyIJ17, IJ18, IJ19, by selectively may operate with controlled IJ21blocking or enabling much lower energy Acoustic nozzles. The inkAcoustic lenses reflections in the ink pressure oscillation can be usedto focus chamber must be may be achieved by tbe sound on the designedfor vibrating the print nozzles head, or preferably by an actuator inthe ink supply. Media The print head is Low power Precision Silverbrook,EP proximity placed in close High accuracy assembly required 0771 658 A2and proximity to the print Simple print head Paper fibers may relatedpatent medium. Selected construction cause problems applications dropsprotrude from Cannot print on the print head further rough substratesthan unselected drops, and contact the print medium. The drop soaks intothe medium fast enough to cause drop separation. Transfer Drops areprinted to a High accuracy Bulky Silverbrook, EP roller transfer rollerinstead Wide range of Expensive 0771 658 A2 and of straight to the printprint substrates can Complex related patent medium. A transfer be usedconstruction applications roller can also be used Ink can be driedTektronix hot for proximity drop on the transfer roller meltpiezoelectric separation. inkjet Any of the IJ series Electro- Anelectric field is Low power Field strength Silverbrook, EP static usedto accelerate Simple print head required for 0771 658 A2 and selecteddrops towards construction separation of small related patent the printmedium. drops is near or applications above air Tone-Jet breakdownDirect A magnetic field is Low power Requires Silverbrook, EP magneticused to accelerate Simple print head magnetic ink 0771 658 A2 and fieldselected drops of construction Requires strong related patent magneticink towards magnetic field applications the print medium. Cross Theprint head is Does not require Requires external IJ06, IJ16 magneticplaced in a constant magnetic materials magnet field magnetic field. Theto be integrated in Current densities Lorenz force in a the print headmay be high, current carrying wire manufacturing resulting in is used tomove the process electromigration actuator. problems Pulsed A pulsedmagnetic Very low power Complex print IJ10 magnetic field is used tooperation is possible head construction field cyclically attract a Smallprint head Magnetic paddle, which pushes size materials required in onthe ink. A small print head actuator moves a catch, which selectivelyprevents the paddle from moving.

ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description AdvantagesDisadvantages Examples None No actuator Operational Many actuatorThermal Bubble mechanical simplicity mechanisms have Ink jetamplification is used. insufficient travel, IJ01, IJ02, IJ06, Theactuator directly or insufficient force, IJ07, IJ16, IJ25, drives thedrop to efficiently drive IJ26 ejection process. the drop ejectionprocess Differential An actuator material Provides greater High stressesare Piezoelectric expansion expands more on one travel in a reducedinvolved IJ03, IJ09, IJ17, bend side than on the other. print head areaCare must be IJ18, IJ19, IJ20, actuator The expansion may be taken thatthe IJ21, IJ22, IJ23, thermal, piezoelectric, materials do not IJ24,IJ27, IJ29, magnetostrictive, or delaminate IJ30, IJ31, IJ32, othermechanism. The Residual bend IJ33, IJ34, IJ35, bend actuator convertsresulting from high IJ36, IJ37, IJ38, a high force low traveltemperature or high IJ39, IJ42, IJ43, actuator mechanism to stressduring IJ44 high travel, lower formation force mechanism. Transient Atrilayer bend Very good High stresses are IJ40, IJ41 bend actuator wherethe two temperature stability involved actuator outside layers are Highspeed, as a Care must be identical. This cancels new drop can be takenthat the bend due to ambient fired before heat materials do nottemperature and dissipates delaminate residual stress. The Cancelsresidual actuator only responds stress of formation to transient heatingof one side or the other. Reverse The actuator loads a Better couplingFabrication IJ05, IJ11 spring spring. When the to the ink complexityactuator is turned off, High stress in the the spring releases. springThis can reverse the force/distance curve of the actuator to make itcompatible with the force/time requirements of the drop ejection.Actuator A series of thin Increased travel Increased Some stackactuators are stacked. Reduced drive fabrication piezoelectric inkjetsThis can be voltage complexity IJ04 appropriate where Increasedactuators require high possibility of short electric field strength,circuits due to such as electrostatic pinholes and piezoelectricactuators. Multiple Multiple smaller Increases the Actuator forces IJ12,IJ13, IJ18, actuators actuators are used force available from may notadd IJ20, IJ22, IJ28, simultaneously to an actuator linearly, reducingIJ42, IJ43 move the ink. Each Multiple efficiency actuator need provideactuators can be only a portion of the positioned to control forcerequired. ink flow accurately Linear A linear spring is used Matches lowRequires print IJ15 Spring to transform a motion travel actuator withhead area for the with small travel and higher travel spring high forceinto a requirements longer travel, lower Non-contact force motion.method of motion transformation Coiled A bend actuator is Increasestravel Generally IJ17, IJ21, IJ34, actuator coiled to provide Reduceschip restricted to planar IJ35 greater travel in a area implementationsreduced chip area. Planar due to extreme implementations are fabricationdifficulty relatively easy to in other orientations. fabricate. FlexureA bend actuator has a Simple means of Care must be IJ10, IJ19, IJ33 bendsmall region near the increasing travel of taken not to exceed actuatorfixture point, which a bend actuator the elastic limit in flexes muchmore the flexure area readily than the Stress remainder of thedistribution is very actuator. The actuator uneven flexing iseffectively Difficult to converted from an accurately model even coilingto an with finite element angular bend, resulting analysis in greatertravel of the actuator tip. Catch The actuator controls a Very lowComplex IJ10 small catch. The catch actuator energy construction eitherenables or Very small Requires external disables movement of actuatorsize force an ink pusher that is Unsuitable for controlled in a bulkpigmented inks manner. Gears Gears can be used to Low force, low Movingparts are IJ13 increase travel at the travel actuators can requiredexpense of duration. be used Several actuator Circular gears, rack Canbe fabricated cycles are required and pinion, ratchets, using standardMore complex and other gearing surface MEMS drive electronics methodscan be used. processes Complex construction Friction, friction, and wearare possible Buckle plate A buckle plate can be Very fast Must staywithin S. Hirata et al, used to change a slow movement elastic limits ofthe “An Ink-jet Head actuator into a fast achievable materials for longUsing Diaphragm motion. It can also device life Microactuator”, converta high force, High stresses Proc. IEEE MEMS, low travel actuatorinvolved Feb. 1996, pp 418- into a high travel, Generally high 423.medium force motion. power requirement IJ18, IJ27 Tapered A taperedmagnetic Linearizes the Complex IJ14 magnetic pole can increase magneticconstruction pole travel at the expense force/distance curve of force.Lever A lever and fulcrum is Matches low High stress IJ32, IJ36, IJ37used to transform a travel actuator with around the fulcrum motion withsmall higher travel travel and high force requirements into a motionwith Fulcrum area has longer travel and no linear movement, lower force.The lever and can be used for can also reverse the a fluid seatdirection of travel. Rotary The actuator is High mechanical Complex IJ28impeller connected to a rotary advantage construction impeller. A smallThe ratio of force Unsuitable for angular deflection of to travel of thepigmented inks the actuator results in actuator can be a rotation of thematched to the impeller vanes, which nozzle requirements push the inkagainst by varying the stationary vanes and number of impeller out ofthe nozzle. vanes Acoustic A refractive or No moving parts Large area1993 Hadimioglu lens diffractive (e.g. zone required et al, EUP 550, 192plate) acoustic lens is Only relevant for 1993 Elrod et al, used toconcentrate acoustic inkjets EUP 572,220 sound waves. Sharp A sharppoint is used Simple Difficult to Tone-jet conductive to concentrate anconstruction fabricate using point electrostatic field. standard VLSIprocesses for a surface ejecting ink- jet Only relevant forelectrostatic ink jets

ACTUATOR MOTION Description Advantages Disadvantages Examples Volume Thevolume of the Simple High energy is Hewlett-Packard expansion actuatorchanges, construction in the typically required to Thermal Ink jetpushing the ink in all case of thermal ink achieve volume CanonBubblejet directions. jet expansion. This leads to thermal stress,cavitation, and kogation in thermal ink jet implementations Linear, Theactuator moves in Efficient High fabrication IJ01, IJ02, IJ04, normal toa direction normal to coupling to ink complexity may be IJ07, IJ11, IJ14chip the print head surface. drops ejected required to achieve surfaceThe nozzle is typically normal to the perpendicular in the line ofsurface motion movement. Parallel to The actuator moves Suitable forFabrication IJ12, IJ13, IJ15, chip parallel to the print planarfabrication complexity IJ33, , IJ34, IJ35, surface head surface. DropFriction IJ36 ejection may still be Stiction normal to the surface.Membrane An actuator with a The effective Fabrication 1982 Howkins pushhigh force but small area of the actuator complexity U.S. area is usedto push a becomes the Actuator size Pat. No. stiff membrane that ismembrane area Difficulty of 4,459,601 in contact with the ink.integration in a VLSI process Rotary The actuator causes Rotary leversDevice IJ05, IJ08, IJ13, the rotation of some may be used to complexityIJ28 element, such a grill or increase travel May have impeller Smallchip area friction at a pivot requirements point Bend The actuator bendsA very small Requires the 1970 Kyser et al U.S. when energized. Thischange in actuator to be made Pat. No. 3,946,398 may be due todimensions can be from at least two 1973 Stemme U.S. differentialthermal converted to a large distinct layers, or to Pat. No. 3,747,120expansion, motion. have a thermal IJ03, IJ09, IJ10, piezoelectricdifference across the IJ19, IJ23, IJ24, expansion, actuator IJ25, IJ29,IJ30, magnetostriction, or IJ31, IJ33, IJ34, other form of relative IJ35dimensional change. Swivel The actuator swivels Allows operationInefficient IJ06 around a central pivot. where the net linear couplingto the ink This motion is suitable force on the paddle motion wherethere are is zero opposite forces Small chip area applied to oppositerequirements sides of the paddle, e.g. Lorenz force. Straighten Theactuator is Can be used with Requires careful IJ26, IJ32 normally bent,and shape memory balance of stresses straightens when alloys where theto ensure that the energized. austenic phase is quiescent bend is planaraccurate Double The actuator bends in One actuator can Difficult to makeIJ36, IJ37, IJ38 bend one direction when be used to power the dropsejected by one element is two nozzles. both bend directions energized,and bends Reduced chip identical. the other way when size. A smallanother element is Not sensitive to efficiency loss energized. ambienttemperature compared to equivalent single bend actuators. ShearEnergizing the Can increase the Not readily 1985 Fishbeck actuatorcauses a shear effective travel of applicable to other U.S. Pat No.4,584,590 motion in the actuator piezoelectric actuator material.actuators mechanisms Radial The actuator squeezes Relatively easy Highforce 1970 Zoltan U.S. Pat. No. con- an ink reservoir, to fabricatesingle required 3,683,212 striction forcing ink from a nozzles fromglass Inefficient constricted nozzle. tubing as Difflcult to macroscopicintegrate with VLSI structures processes Coil/ A coiled actuator Easy tofabricate Difficult to IJ17, IJ21, IJ34, uncoil uncoils or coils more asa planar VLSI fabricate for non- IJ35 tightly. The motion of processplanar devices the free end of the Small area Poor out-of-plane actuatorejects the ink. required, therefore stiffness low cost Bow The actuatorbows (or Can increase the Maximum travel IJ16, IJ18, IJ27 buckles) inthe middle speed of travel is constrained when energized. MechanicallyHigh force rigid required Push-Pull Two actuators control The structureis Not readily IJ18 a shutter. One actuator pinned at both ends,suitable for inkjets pulls the shutter, and so has a high out-of- whichdirectly push the other pushes it. plane rigidity the ink Curl A set ofactuators curl Good fluid flow Design IJ20, IJ42 inwards inwards toreduce the to the region behind complexity volume of ink that theactuator they enclose. increases efflciency Curl A set of actuators curlRelatively simple Relatively large IJ43 outwards outwards, pressurizingconstruction chip area ink in a chamber surrounding the actuators, andexpelling ink from a nozzle in the chamber. Iris Multiple vanes encloseHigh efficiency High fabrication IJ22 a volume of ink. These Small chiparea complexity simultaneously rotate, Not suitable for reducing thevolume pigmented inks between the vanes. Acoustic The actuator vibratesThe actuator can Large area 1993 Hadimioglu vibration at a highfrequency. be physically distant required for et al, EUP 550,192 fromthe ink efficient operation 1993 Elrod et al, at useful frequencies EUP572,220 Acoustic coupling and crosstalk Complex drive circuitry Poorcontrol of drop volume and position None In various ink jet No movingparts Various other Silverbrook, EP designs the actuator tradeoffs are0771 658 A2 and does not move. required to related patent eliminatemoving applications parts Tone-jet

NOZZLE REFILL METHOD Description Advantages Disadvantages ExamplesSurface This is the normal way Fabrication Low speed Thermal inkjettension that inkjets are simplicity Surface tension Piezoelectric inkrefilled. After the Operational force reiatively jet actuator isenergized, simplicity small compared to IJ01-IJ07, IJ10- it typicallyreturns actuator force IJ14, 1J16, IJ20, rapidly to its normal Longrefill time IJ22-IJ45 position. This rapid usually dominates returnsucks in air the total repetition through the nozzle rate opening. Theink surface tension at the nozzle then exerts a small force restoringthe meniscus to a minimum area. This force refills the nozzle. ShutteredInk to the nozzle High speed Requires IJ08, IJ13, IJ15, oscillatingchamber is provided at Low actuator common ink IJ17, IJ18, IJ19, ink apressure that energy, as the pressure oscillator IJ21 pressureoscillates at twice the actuator need only May not be drop ejection openor close the suitable for frequency. When a shutter, instead ofpigmented inks drop is to be ejected, ejecting the ink drop the shutteris opened for 3 half cycles: drop ejection, actuator return, and refill.The shutter is then closed to prevent the nozzle chamber emptying duringthe next negative pressure cycle. Refill After the main High speed, asRequires two IJ09 actuator actuator has ejected a the nozzle isindependent drop a second (refill) actively refilled actuators pernozzle actuator is energized. The refill actuator pushes ink into thenozzle chamber. The refill actuator returns slowly, to prevent itsreturn from emptying the chamber again. Positive The ink is held aslight High refill rate, Surface spill Silverbrook, EP ink positivepressure. therefore a high must be prevented 0771 658 A2 and pressureAfter the ink drop is drop repetition rate Highly related patentejected, the nozzle is possible hydrophobic print applications chamberfills quickly head surfaces are Alternative for:, as surface tension andrequired IJ01-IJ07, IJ10-IJ14, ink pressure both IJ16, IJ20, IJ22-IJ45operate to refill the nozzle.

METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Description AdvantagesDisadvantages Examples Long inlet The ink inlet channel Designsimplicity Restricts refill Thermal ink jet channel to the nozzlechamber Operational rate Piezoelectric ink is made long and simplicityMay result in a jet relatively narrow, Reduces relatively large chipIJ42, IJ43 relying on viscous crosstalk area drag to reduce inlet Onlypartially back-flow. effecflve Positive The ink is under a Dropselection Requires a Silverbrook, EP ink positive pressure, so andseparation method (such as a 0771 658 A2 and pressure that in thequiescent forces can be nozzle rim or related patent state some of theink reduced effective applications drop already protrudes Fast refilltime hydrophobizing, or Possible from the nozzle. both) to preventoperation of the This reduces the flooding of the following: IJ01-pressure in the nozzle ejection surface of IJ07, IJ09-IJ12, chamberwhich is the print head. IJ14, IJ16, IJ20, required to eject a IJ22, ,IJ23-IJ34, certain volume of ink. IJ36-IJ41, IJ44 The reduction inchamber pressure results in a reduction in ink pushed out through theinlet. Baffle One or more baffles The refill rate is Design HP ThermalInk are placed in the inlet not as restricted as complexity Jet inkflow. When the the long inlet May increase Tektronix actuator isenergized, method. fabrication piezoelectric ink jet the rapid inkReduces complexity (e.g. movement creates crosstalk Tektronix hot melteddies which restrict Piezoelectric print the flow through the heads).inlet. The slower refill process is unrestricted, and does not result ineddies. Flexible In this method recently Significantly Not applicable toCanon flap disclosed by Canon, reduces back-flow most ink jet restrictsthe expanding actuator for edge-shooter configurations inlet (bubble)pushes on a thermal ink jet Increased flexible flap that devicesfabrication restricts the inlet. complexity Inelastic deformation ofpolymer flap results in creep over extended use Inlet filter A filter islocated Additional Restricts refill IJ04, IJ12, IJ24, between thie inkinlet advantage of ink rate IJ27, IJ29, IJ30 and the nozzle filtrationMay result in chamber. The filter Ink filter may be complex has amultitude of fabricated with no construction small holes or slots,additional process restricting ink flow. steps The filter also removesparticles which may block the nozzle. Small inlet The ink inlet channelDesign simplicity Restricts refill IJ02, IJ37, IJ44 compared to thenozzle chamber rate to nozzle has a substantially May result in asmaller cross section relatively large chip than that of the nozzle area, resulting in easier ink Only partially egress out of the effectivenozzle than out of the inlet. Inlet A secondary actuator Increases speedRequires separate IJ09 shutter controls the position of of the ink-jetprint refill actuator and a shutter, closing off head operation drivecircuit the ink inlet when the main actuator is energized. The inlet Themethod avoids the Back-flow Requires careful IJ01, IJ03, 1J05, isproblem of inlet back- problem is design to minimize IJ06, IJ07, IJ10,located flow by arranging the eliminated the negative IJ11, IJ14, IJ16,behind the ink-pushing surface of pressure behind the IJ22, IJ23, IJ25,ink- the actuator between paddle IJ28, IJ31, IJ32, pushing the inlet andthe IJ33, 1334, IJ35, surface nozzle. IJ36, IJ39, IJ40, IJ41 Part of theThe actuator and a Significant Small increase in IJ07, IJ20, IJ26,actuator wall of the ink reductions in back- fabrication IJ38 moves tochamber are arranged flow can be complexity shut so that the motion ofachieved off the the actuator closes off Compact designs inlet theinlet. possible Nozzle In some configurations Ink back-flow None relatedto Silverbrook, EP actuator of inkjet, there is no problem is inkback-flow on 0771 658 A2 and does not expansion or eliminated actuationrelated patent result movement of an applications in ink actuator whichmay Valve-jet back-flow cause ink back-flow Tonejet through the inlet.

NOZZLE CLEARING METHOD Description Advantages Disadvantages ExamplesNormal All of the nozzles are No added May not be Most ink jet nozzlefired periodically, complexity on the sufficient to systems firingbefore the ink has a print head displace dried ink IJ01, IJ02, IJ03,chance to dry. When IJ04, IJ05, IJ06, not in use the nozzles IJ07, IJ09,IJ10, are sealed (capped) IJ11, IJ12, IJ14, against air. IJ16, IJ20,IJ22, The nozzle firing is IJ23, IJ24, IJ25, usually performed IJ26,IJ27, IJ28, during a special IJ29, IJ30, IJ31, clearing cycle, afterIJ32, IJ33, IJ34, first moving the print IJ36, IJ37, IJ38, head to acleaning IJ39, IJ40,, IJ41, station. IJ42, IJ43, IJ44,, IJ45 Extra Insystems which heat Can be highly Requires higher Silverbrook, EP powerto the ink, but do not boil effective if the drive voltage for 0771 658A2 and ink heater it under normal heater is adjacent to clearing relatedpatent situations, nozzle the nozzle May require applications clearingcan be larger drive achieved by over- transistors powering the heaterand boiling ink at the nozzle. Rapid The actuator is fired in Does notrequire Effectiveness May be used success- rapid succession. In extradrive circuits depends with: IJ01, IJ02, ion some configurations, on theprint head substantially upon IJ03, IJ04, IJ05, of actuator this maycause heat Can be readily the configuration of IJ06, IJ07, IJ09, pulsesbuild-up at the nozzle controlled and the ink jet nozzle IJ10, IJ11,IJ14, which boils the ink, initiated by digital IJ16, IJ20, IJ22,clearing the nozzle. In logic IJ23, IJ24, IJ25, offer situations, it mayIJ27, IJ28, IJ29, cause sufficient IJ30, IJ31, IJ32, vibrations todislodge IJ33, IJ34, IJ36, clogged nozzles. IJ37, IJ38, IJ39, IJ40,IJ41, IJ42, IJ43, IJ44, IJ45 Extra Where an actuator is A simple Notsuitable May be used power to not normally driven to solution wherewhere there is a with: IJ03, IJ09, ink the limit of its motion,applicable hard limit to IJ16, IJ20, IJ23, pushing nozzle clearing maybe actuator movement IJ24, IJ25, IJ27, actuator assisted by providingIJ29, IJ30, IJ31, an enhanced drive IJ32, IJ39, IJ40, signal to theactuator. IJ41, IJ42, IJ43, IJ44, IJ45 Acoustic An ultrasonic wave is Ahigh nozzle High IJ08, IJ13, IJ15, resonance applied to the ink clearingcapability implementation cost IJ17, IJ18, IJ19, chamber. This wave iscan be achieved if system does not IJ21 of an appropriate May be alreadyinclude an amplitude and implemented at very acoustic actuator frequencyto cause low cost in systems sufficient force at the which alreadynozzle to clear include acoustic blockages. This is actuators easiest toachieve if the ultrasonic wave is at a resonant frequency of the inkcavity. Nozzle A microfabricated Can clear Accurate Silverbrook, EPclearing plate is pushed against severely clogged mechanical 0771 658 A2and plate the nozzles. The plate nozzles alignment is related patent hasa post for every required applications nozzle. A post moves Moving partsare through each nozzle, required displacing dried ink. There is risk ofdamage to the nozzles Accurate fabrication is required Ink The pressureof the ink May be effective Requires May be used pressure is temporarilywhere other pressure pump or with all IJ pulse increased so that inkmethods cannot be other pressure series ink jets streams from all of theused actuator nozzles. This may be Expensive used in conjunctionWasteful of ink with actuator energizing. Print head A flexible ‘blade’is Effective for Difficult to use if Many inkjet wiper wiped across theprint planar print head print head surface is systems head surface. Thesurfaces non-planar or very blade is usually Low cost fragile fabricatedfrom a Requires flexible polymer, e.g. mechanical parts rubber orsynthetic Blade can wear elastomer. out in high volume print systemsSeparate A separate heater is Can be effective Fabrication Can be usedwith ink boiling provided at the nozzle where other nozzle complexitymany IJ series ink heater although the normal clearing methods jets drope-ection cannot be used mechanism does not Can be require it. Theheaters implemented at no do not require additional cost in individualdrive some ink jet circuits, as many configurations nozzles can becleared simultaneously, and no imaging is reguired.

NOZZLE LATE CONSTRUCTION Description Advantages Disadvantages ExamplesElectro- A nozzle plate is Fabrication High Hewlett Packard formedseparately fabricated simplicity temperatures and Thermal Ink jet nickelfrom electroformed pressures are nickel, and bonded to required to bondthe print head chip. nozzle plate Minimum thickness constraintsDifferential thermal expansion Laser Individual nozzle No masks Eachhole must Canon Bubblejet ablated or holes are ablated by an required beindividually 1988 Sercel et drilled intense UV Iaser in a Can be quitefast formed al., SPIE, Vol. 998 polymer nozzle plate, which is Somecontrol Special Excimer Beam typically a polymer over nozzle profileequipment required Applications, pp. such as polyimide or is possibleSlow where there 76-83 polysulphone Equipment are many thousands 1993Watanabe required is relatively of nozzles per print et al., U.S. Pat.No. low cost head 5,208,604 May produce thin burrs at exit holes SiliconA separate nozzle High accuracy is Two part K. Bean, IEEE micro- plateis attainable construction Transactions on machined micromachined ftomHigh cost Electron Devices, single crystal silicon, Requires Vol. ED-25,No. 10, and bonded to the precision alignment 1978, pp 1185-1195 printhead wafer. Nozzles may be Xerox 1990 clogged by adhesive Hawkins etal., U.S. Pat. No. 4,899,181 Glass Fine glass capillaries No expensiveVery small 1970 Zoltan U.S. Pat. No. capillaries are drawn from glassequipment required nozzle sizes are 3,683,212 tubing. This method Simpleto make difficult to form has been used for single nozzles Not suitedfor making individual mass production nozzles, but is difficult to usefor bulk manufacturing of print heads with thousands of nozzles.Monolithic, The nozzle plate is High accuracy Requires Silverbrook, EPsurface deposited as a layer (<1 μm) sacrificial layer 0771 658 A2 andmicro- using standard VLSI Monolithic under the nozzle related patentmachined deposition techniques. Low cost plate to form the applicationsusing VLSI Nozzles are etched in Existing nozzle chamber IJ01, IJ02,IJ04, litho- the nozzle plate using processes can be Surface may beIJ11, IJ12, IJ17, graphic VLSI lithography and used fragile to the touchIJ18, IJ20, IJ22, processes etching. IJ24, IJ27, IJ28, IJ29, IJ30, IJ31,IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44Monolithic, The nozzle plate is a High accuracy Requires long IJ03,IJ05, IJ06, etched buried etch stop in the (<1 μm) etch times I307,IJ08, I309, through wafer. Nozzle Monolithic Requires a IJ10, IJ13,IJ14, substrate chambers are etched in Low cost support wafer IJ15,IJ16, IJ19, the front of the wafer, No differential IJ21, IJ23, IJ25,and the wafer is expansion IJ26 thinned from the back side. Nozzles arethen etched in the etch stop layer. No nozzle Various methods have Nonozzles to Difficult to Ricoh 1995 plate been tried to eliminate becomeclogged control drop Sekiya et al U.S. Pat. No. the nozzles entirely, toposition accurately 5,412,413 prevent nozzle Crosstalk 1993 Hadimiogluclogging. These problems et al EUP 550,192 include thermal bubble 1993Elrod et al mechanisms and EUP 572,220 acoustic lens mechanisms TroughEach drop ejector has Reduced Drop firing IJ35 a trough throughmanufacturing direction is sensitive which a paddle moves. complexity towicking. There is no nozzle Monolithic plate. Nozzle slit Theelimination of No nozzles to Difficult to 1989 Saito et al instead ofnozzle holes and become clogged control drop U.S. Pat. No. 4,799,068individual replacement by a slit position accurately nozzlesencompassing many Crosstalk actuator positions problems reduces nozzleclogging, but increases crosstalk due to ink surface waves

DROP EJECTION DIRECTION Description Advantages Disadvantages ExamplesEdge Ink flow is along the Simple Nozzles linijted Canon Bubblejet(‘edge surface of the chip, Construction to edge 1979 Endo et al GBshooter’) and ink drops are No Silicon High resolution patent 2,007,162ejected from the chip etching required is difficult Xerox heater-in-edge. Good heat Fast color pit 1990 Hawkins et sinking via substrateprinting requires al U.S. Pat. No. 4,899,181 Mechanically one print headper Tone-jet strong color Ease of chip handing Surface Ink flow is alongthe No bulk Silicon Maximum ink Hewlett-Packard (‘roof surface of thechip, etching required flow is severely TJI 1982 Vaught et shooter’) andink drops are Silicon can make restricted al U.S. Pat. No. 4,490,728ejected from the chip an effective heat IJ02, IJ11, IJ12, surface,normal to the sink IJ20, IJ22 plane of the chip. Mechanical strengthThrough Ink flow is through the High ink flow Requires bulk Silverbrook,EP chip, chip, and ink drops are Suitable for silicon etching 0771 658A2 and forward ejected from the front pagewidth print related patent(‘up surface of the chip. heads applications shooter’) High nozzle IJ04,IJ17, IJ18, packing density IJ24, IJ27-IJ45 therefore low manufacturingcost Through Ink flow is through the High ink flow Requires wafer IJ01,IJ03, IJ05, chip, chip, and ink drops are Suitable for thinning IJ06,IJ07, IJ08, reverse ejected from the rear pagewidth print Requiresspecial IJ09, IJ10, IJ13, (‘down surface of the chip. heads handlingduring IJ14, IJ15, IJ16, shooter’) High nozzle manufacture IJ19, IJ21,IJ23, packing density IJ25, IJ26 therefore low manufacturing costThrough Ink flow is through the Suitable for Pagewidth print EpsonStylus actuator actuator, which is not piezoelectric print heads requireTektronix hot fabricated as part of heads several thousand meltpiezoelectric the same substrate as connections to drive ink jets thedrive transistors. circuits Cannot be manufactured in standard CMOS fabsComplex assembly required

INK TYPE Description Advantages Disadvantages Examples Aqueous, Waterbased ink which Environmentally Slow drying Most existing ink dyetypically contains: friendly Corrosive jets water, dye, surfactant, Noodor Bleeds on paper All IJ series ink humectant, and May jets biocide.strikethrough Silverbrook, EP Modern ink dyes have Cockles paper 0771658 A2 and high water-fastness, related patent light fastnessapplications Aqueous, Water based ink which Environmentally Slow dryingIJ02, IJ04, IJ21, pigment typically contains: friendly Corrosive IJ26,IJ27, IJ30 water, pigment, No odor Pigment may Silverbrook, EPsurfactant, humectant, Reduced bleed clog nozzles 0771 658 A2 and andbiocide. Reduced wicking Pigment may related patent Pigments have anReduced clog actuator applications advantage in reduced strikethroughmechanisms Piezoelectric ink- bleed, wicking and Cockies paper jetsstrikethrough. Thermal ink jets (with significant restrictions) MethylMEK is a highly Very fast drying Odorous All IJ series ink Ethylvolatile solvent used Prints on various Flammable jets Ketone forindustrial printing substrates such as (MEK) on difficult surfacesmetals and plastics such as aluminum cans. Alcohol Alcohol based inksFast drying Slight oddr. All IJ series ink (ethanol, 2- can be usedwhere the Operates at sub- Flammable jets butanol, printer must operateat freezing and others) temperatures below temperatures the freezingpoint of Reduced paper water. An example of cockle this is in-camera Lowcost consumer photographic printing. Phase The ink is solid at No dryingtime- High viscosity Tektronix hot change room temperature, and inkinstantly freezes Printed ink melt piezoelectric (hot melt) is melted inthe print on the print medium typically has a ink jets head beforejetting. Almost any print ‘waxy’ feel 1989 Nowak Hot melt inks aremedium can be used Printed pages U.S. Pat. No. 4,820,346 usually waxbased, No paper cockle may ‘block’ All IJ series ink with a meltingpoint occurs Ink temperature jets around 80° C. After No wicking may beabove the jetting the ink freezes occurs curie point of almost instantlyupon No bleed occurs permanent magnets contacting the print Nostrikethrough Ink heaters medium or a transfer occurs consume powerroller. Long warm-up time Oil Oil based inks are High solubility Highviscosity: All IJ series ink extensively used in medium for some this isa significant jets offset printing. They dyes limitation for use in haveadvantages in Does not cockle ink jets, which improved paper usuallyrequire a characteristics on Does not wick low viscosity. Some paper(especially no through paper short chain and wicking or cockle).multi-branched oils Oil soluble dies and have a sufficiently pigmentsare required. low viscosity. Slow drying Micro- A microemulsion is aStops ink bleed Viscosity higher All IJ series ink emulsion stable, selfforming High dye than water jets emulsion of oil water, solubility Costis slighdy and surfactant. The Water, d354 and higher than watercharacteristic drop size amphiphilic soluble based ink is less than 100nm, dies can be used High surfactant and is determined by Can stabilizeconcentration the prefeffed curvature pigment required (around of thesurfactant. suspensions 5%)

What is claimed is:
 1. A fluid supply unit for supplying a plurality ofdifferent fluids to a plurality of supply slots, said supply slots beingspaced apart at substantially regular intervals in an interleavedmanner, said fluid supply unit comprising: an elongate element with arecess defined in one surface of the elongate element, the supply slotsopening into said recess; fluid inlet means for each of said pluralityof different fluids arranged at one end of the elongate element; a mainchannel flow means, defined at least partially by the elongate element,for each of said different fluids, a main channel flow means being incommunication with each of said fluid inlet means; and a sub-channelflow means extending from each of the main channel flow means forplacing each of said supply slots in communication with a correspondingmain channel flow means; wherein the element is a one-piece mouldedelement, the number of fluids to be supplied is greater than 2 and atleast one of said main channel flow means runs along said one surface ofthe elongate element and others of said main channel flow means runalong an opposed surface of said elongate element, the sub-channel flowmeans being in fluid communication with said supply slots by means ofthrough-holes through the surfaces of said elongate element.
 2. A fluidsupply unit as claimed in claim 1 which is plastic injection moulded. 3.A fluid supply unit as claimed in claim 1 wherein a pitch rate of saidslots is substantially less than or equal to 1,000 slots per inch.
 4. Afluid supply unit as claimed in claimed 1 wherein the supply slots arearranged in a collection of slots and the collection extendssubstantially the width of a photograph.
 5. A fluid supply unit asclaimed in claim 1 further comprising: a plurality of roller slot meansfor the reception of one or more pinch rollers and wherein the pluralityof different fluids comprise inks and said rollers are utilised tocontrol the passage of a print media across a print-head incommunication with said supply slots.
 6. A fluid supply unit as claimedin claim 5 wherein said supply slots are divided into correspondingcolour slots with each series of colour slots being arranged in columns.7. A fluid supply unit as claimed in claim 1 wherein at least one ofsaid main channel flow means is exposed when fabricated and is sealed bymeans of utilising sealing tape to seal the exposed surface of saidchannel.
 8. A fluid supply unit as claimed in claim 1 which is furtherprovided with a TAB slot for the reception of Tape Automated Bonded(TAB) wires.